390 lines
14 KiB
C++
390 lines
14 KiB
C++
/*
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This source is published under the following 3-clause BSD license.
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Copyright (c) 2012 - 2013, Lukas Hosek and Alexander Wilkie
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* None of the names of the contributors may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* ============================================================================
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This file is part of a sample implementation of the analytical skylight and
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solar radiance models presented in the SIGGRAPH 2012 paper
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"An Analytic Model for Full Spectral Sky-Dome Radiance"
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and the 2013 IEEE CG&A paper
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"Adding a Solar Radiance Function to the Hosek Skylight Model"
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both by
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Lukas Hosek and Alexander Wilkie
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Charles University in Prague, Czech Republic
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Version: 1.4a, February 22nd, 2013
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Version history:
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1.4a February 22nd, 2013
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Removed unnecessary and counter-intuitive solar radius parameters
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from the interface of the colourspace sky dome initialisation functions.
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1.4 February 11th, 2013
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Fixed a bug which caused the relative brightness of the solar disc
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and the sky dome to be off by a factor of about 6. The sun was too
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bright: this affected both normal and alien sun scenarios. The
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coefficients of the solar radiance function were changed to fix this.
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1.3 January 21st, 2013 (not released to the public)
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Added support for solar discs that are not exactly the same size as
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the terrestrial sun. Also added support for suns with a different
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emission spectrum ("Alien World" functionality).
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1.2a December 18th, 2012
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Fixed a mistake and some inaccuracies in the solar radiance function
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explanations found in ArHosekSkyModel.h. The actual source code is
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unchanged compared to version 1.2.
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1.2 December 17th, 2012
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Native RGB data and a solar radiance function that matches the turbidity
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conditions were added.
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1.1 September 2012
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The coefficients of the spectral model are now scaled so that the output
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is given in physical units: W / (m^-2 * sr * nm). Also, the output of the
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XYZ model is now no longer scaled to the range [0...1]. Instead, it is
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the result of a simple conversion from spectral data via the CIE 2 degree
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standard observer matching functions. Therefore, after multiplication
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with 683 lm / W, the Y channel now corresponds to luminance in lm.
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1.0 May 11th, 2012
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Initial release.
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Please visit http://cgg.mff.cuni.cz/projects/SkylightModelling/ to check if
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an updated version of this code has been published!
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============================================================================ */
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/*
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All instructions on how to use this code are in the accompanying header file.
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*/
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#include "sky_model.h"
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#include "sky_model_data.h"
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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CCL_NAMESPACE_BEGIN
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// Some macro definitions that occur elsewhere in ART, and that have to be
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// replicated to make this a stand-alone module.
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#ifndef MATH_PI
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#define MATH_PI 3.141592653589793
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#endif
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#ifndef MATH_DEG_TO_RAD
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#define MATH_DEG_TO_RAD ( MATH_PI / 180.0 )
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#endif
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#ifndef DEGREES
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#define DEGREES * MATH_DEG_TO_RAD
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#endif
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#ifndef TERRESTRIAL_SOLAR_RADIUS
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#define TERRESTRIAL_SOLAR_RADIUS ( ( 0.51 DEGREES ) / 2.0 )
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#endif
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#ifndef ALLOC
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#define ALLOC(_struct) ((_struct *)malloc(sizeof(_struct)))
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#endif
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// internal definitions
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typedef double *ArHosekSkyModel_Dataset;
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typedef double *ArHosekSkyModel_Radiance_Dataset;
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// internal functions
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static void ArHosekSkyModel_CookConfiguration(
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ArHosekSkyModel_Dataset dataset,
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ArHosekSkyModelConfiguration config,
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double turbidity,
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double albedo,
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double solar_elevation
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)
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{
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double * elev_matrix;
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int int_turbidity = (int)turbidity;
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double turbidity_rem = turbidity - (double)int_turbidity;
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solar_elevation = pow(solar_elevation / (MATH_PI / 2.0), (1.0 / 3.0));
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// alb 0 low turb
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elev_matrix = dataset + ( 9 * 6 * (int_turbidity-1) );
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for( unsigned int i = 0; i < 9; ++i )
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{
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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config[i] =
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(1.0-albedo) * (1.0 - turbidity_rem)
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* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
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5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
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pow(solar_elevation, 5.0) * elev_matrix[i+45]);
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}
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// alb 1 low turb
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elev_matrix = dataset + (9*6*10 + 9*6*(int_turbidity-1));
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for(unsigned int i = 0; i < 9; ++i)
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{
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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config[i] +=
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(albedo) * (1.0 - turbidity_rem)
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* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
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5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
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pow(solar_elevation, 5.0) * elev_matrix[i+45]);
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}
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if(int_turbidity == 10)
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return;
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// alb 0 high turb
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elev_matrix = dataset + (9*6*(int_turbidity));
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for(unsigned int i = 0; i < 9; ++i)
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{
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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config[i] +=
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(1.0-albedo) * (turbidity_rem)
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* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
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5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
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pow(solar_elevation, 5.0) * elev_matrix[i+45]);
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}
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// alb 1 high turb
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elev_matrix = dataset + (9*6*10 + 9*6*(int_turbidity));
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for(unsigned int i = 0; i < 9; ++i)
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{
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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config[i] +=
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(albedo) * (turbidity_rem)
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* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
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5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
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pow(solar_elevation, 5.0) * elev_matrix[i+45]);
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}
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}
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static double ArHosekSkyModel_CookRadianceConfiguration(
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ArHosekSkyModel_Radiance_Dataset dataset,
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double turbidity,
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double albedo,
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double solar_elevation
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)
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{
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double* elev_matrix;
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int int_turbidity = (int)turbidity;
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double turbidity_rem = turbidity - (double)int_turbidity;
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double res;
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solar_elevation = pow(solar_elevation / (MATH_PI / 2.0), (1.0 / 3.0));
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// alb 0 low turb
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elev_matrix = dataset + (6*(int_turbidity-1));
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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res = (1.0-albedo) * (1.0 - turbidity_rem) *
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( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
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5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
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pow(solar_elevation, 5.0) * elev_matrix[5]);
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// alb 1 low turb
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elev_matrix = dataset + (6*10 + 6*(int_turbidity-1));
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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res += (albedo) * (1.0 - turbidity_rem) *
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( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
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5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
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pow(solar_elevation, 5.0) * elev_matrix[5]);
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if(int_turbidity == 10)
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return res;
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// alb 0 high turb
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elev_matrix = dataset + (6*(int_turbidity));
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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res += (1.0-albedo) * (turbidity_rem) *
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( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
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5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
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pow(solar_elevation, 5.0) * elev_matrix[5]);
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// alb 1 high turb
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elev_matrix = dataset + (6*10 + 6*(int_turbidity));
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//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
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res += (albedo) * (turbidity_rem) *
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( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
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5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
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10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
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10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
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5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
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pow(solar_elevation, 5.0) * elev_matrix[5]);
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return res;
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}
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static double ArHosekSkyModel_GetRadianceInternal(
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ArHosekSkyModelConfiguration configuration,
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double theta,
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double gamma
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)
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{
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const double expM = exp(configuration[4] * gamma);
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const double rayM = cos(gamma)*cos(gamma);
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const double mieM = (1.0 + cos(gamma)*cos(gamma)) / pow((1.0 + configuration[8]*configuration[8] - 2.0*configuration[8]*cos(gamma)), 1.5);
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const double zenith = sqrt(cos(theta));
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return (1.0 + configuration[0] * exp(configuration[1] / (cos(theta) + 0.01))) *
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(configuration[2] + configuration[3] * expM + configuration[5] * rayM + configuration[6] * mieM + configuration[7] * zenith);
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}
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void arhosekskymodelstate_free(
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ArHosekSkyModelState * state
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)
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{
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free(state);
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}
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double arhosekskymodel_radiance(
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ArHosekSkyModelState * state,
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double theta,
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double gamma,
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double wavelength
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)
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{
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int low_wl = (wavelength - 320.0 ) / 40.0;
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if ( low_wl < 0 || low_wl >= 11 )
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return 0.0f;
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double interp = fmod((wavelength - 320.0 ) / 40.0, 1.0);
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double val_low =
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ArHosekSkyModel_GetRadianceInternal(
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state->configs[low_wl],
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theta,
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gamma
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)
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* state->radiances[low_wl]
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* state->emission_correction_factor_sky[low_wl];
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if ( interp < 1e-6 )
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return val_low;
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double result = ( 1.0 - interp ) * val_low;
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if ( low_wl+1 < 11 )
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{
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result +=
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interp
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* ArHosekSkyModel_GetRadianceInternal(
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state->configs[low_wl+1],
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theta,
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gamma
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)
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* state->radiances[low_wl+1]
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* state->emission_correction_factor_sky[low_wl+1];
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}
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return result;
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}
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// xyz and rgb versions
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ArHosekSkyModelState * arhosek_xyz_skymodelstate_alloc_init(
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const double turbidity,
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const double albedo,
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const double elevation
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)
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{
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ArHosekSkyModelState * state = ALLOC(ArHosekSkyModelState);
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state->solar_radius = TERRESTRIAL_SOLAR_RADIUS;
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state->turbidity = turbidity;
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state->albedo = albedo;
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state->elevation = elevation;
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for( unsigned int channel = 0; channel < 3; ++channel )
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{
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ArHosekSkyModel_CookConfiguration(
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datasetsXYZ[channel],
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state->configs[channel],
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turbidity,
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albedo,
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elevation
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);
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state->radiances[channel] =
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ArHosekSkyModel_CookRadianceConfiguration(
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datasetsXYZRad[channel],
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turbidity,
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albedo,
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elevation
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);
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}
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return state;
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}
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CCL_NAMESPACE_END
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